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In Search of Common Ground: Expert Judgments on Gun Policy Effects

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As our review of the existing literature demonstrated, there is very little scientific evidence available to support the decisions that policymakers and the public must make about whether to implement or change various gun policies. Without strong scientific evidence, policymakers and the public rely heavily on what advocates or social scientists believe the effects of policies are most likely to be. The opinions of these gun policy experts are an important influence on gun policy debates and decisions because people believe that the experts have an especially well-informed understanding of the gun polices under consideration, how similar laws have performed historically, and how specific policies would affect particular stakeholder groups.

Different communities of gun policy experts have sharply divided views on many gun policies, as often becomes clear in the debates that occur when states and the federal government consider new gun legislation. Less clear is whether there are laws or policies where such differences are less stark, or whether there may be a combination of policies that experts of every stripe could regard as an improvement over existing policies. Finally, it has not been clear whether experts disagree about what objectives gun policies should be trying to achieve or whether they agree on the objectives but disagree on which policies are most likely to achieve those objectives. If the experts chiefly disagree on the latter, this suggests a role for new and better scientific study of the true effects of gun policies.

To begin to answer these questions, RAND researchers surveyed nearly 100 gun policy experts on what they believed the effects of the following 15 gun policies would be on 12 different outcomes.

Note: The policies listed here are the same as those evaluated in our research review, except the survey also included firearm taxes and a media campaign to prevent child access to firearms. In some cases, the survey asked about a policy that was characterized slightly differently in our review of the scientific evidence; for example, we distinguish between background checks and universal background checks and between permitless carry and various forms of concealed-carry laws. The outcomes listed here are also the same as those evaluated in our research review, except the survey did not include officer-involved shootings and did include property crime, the right to bear arms, individuals' privacy, and satisfaction of gun ownership.

To help characterize major differences among groups of gun policy experts, we sought input from experts likely to have divergent views. We invited legislative analysts working for gun policy advocacy organizations on both sides of the debate to participate, including from the National Rifle Association, the Brady Campaign to Prevent Gun Violence, the National Shooting Sports Foundation, Everytown for Gun Safety, and many others. We also reached out to professional associations that have advocated for various gun policies in the past, including the International Association of Chiefs of Police, the National Sheriffs’ Association, the American Academy of Pediatrics, the National Alliance on Mental Illness, and others. And we invited gun policy researchers with a track record of publishing scientific research in this area, as well as staff working in congressional committees that consider gun legislation. For more information on the methods used to generate our sample and analyze the results, read about our survey methodology.

We asked each survey respondent to provide a quantitative estimate of how much the introduction of some of the policies listed above would alter each of the outcomes. We also asked them to indicate their overall opinion of each policy, and from their answers we quickly identified two sharply divided groups. As it turned out, each of these groups also differed in their views of which advocacy organizations had gun policy positions closest to their own. The smaller of the two groups (16 experts) strongly identified with the policy positions of the National Rifle Association, the Second Amendment Foundation, and the National Shooting Sports Foundation. This group also favored policies—such as stand-your-ground laws, permitless carry, and the elimination of gun-free zones—that we interpret as more permissive in their approach to gun access and use. Therefore, for simplicity, we refer to experts in this group as favoring permissive gun policies.

The second group (79 experts) identified most strongly with the policy positions of the Brady Campaign to Prevent Gun Violence, Everytown for Gun Safety, the Violence Policy Center, and the Coalition to Stop Gun Violence. In addition, this group preferred policies—such as universal background checks, requiring a license to purchase firearms or ammunition, and requiring the surrender of firearms by prohibited possessors—that we interpret as more restrictive in their approach to gun access and use. Therefore, we refer to experts in this group as favoring restrictive gun policies. Because this was not a representative survey, the difference in the sizes of these groups provides no information about the relative numbers of experts in the community whose views align with one or the other perspective. The difference in size does not bias our results toward the views of the larger group, because we analyze views in each group separately. That is, we never combine responses from the two groups to construct any kind of "typical" opinion across all experts.

Policies with the least agreement

In most cases, the policies most favored by experts in the permissive group received the poorest ratings by those in the restrictive group, and vice versa. However, the two groups were often in greater agreement when estimating whether each policy would increase or decrease each outcome, usually differing only on the magnitude of such changes. Indeed, across 134 judgments about the effects of the policies, only 12 times (9 percent) did the median judgment for each group disagree on the direction of the effect, where, for example, one group thought a law would increase homicide rates, and the other group thought the law would decrease these rates. More than half of these 12 instances concerned two policies: permitless carry and the elimination of gun-free zones. Those in the permissive group expected these policies to reduce firearm homicides; mass shootings; other violent crime; and, in the case of permitless carry, property crime. Those in the restrictive group expected the opposite.

When we looked at each group of experts’ overall opinions of the policies, there was comparatively strong agreement for the following four policies: expanded mental health prohibitions, required reporting of lost or stolen firearms, a media campaign to prevent child access, and surrender of firearms by prohibited possessors. For each of these policies, the members of the permissive group typically regarded them as neutral (neither favorable nor unfavorable), while the restrictive group gave them positive ratings. Moreover, there was relatively strong agreement between expert groups on the direction and magnitude of the likely effects of these policies on the outcomes examined.

You can explore how the experts think that policies might affect the outcomes in each state and nationally using RAND’s gun policy comparison tool, which is based on the responses from our survey of gun policy experts. In addition, using a series of assumptions (documented in the survey report) for combining experts’ effect estimates across multiple policies, we can estimate the experts’ views on the effects of different combinations of policies if they were enacted or rescinded in every U.S. state.

Experts in Both Groups Appear to Share Objectives

Views on the merits of the policies we studied are strikingly polarized, with almost no overlap in overall opinion ratings between the two groups of experts. But why do experts disagree about which policies are good or bad? Do the experts agree on what the objectives of gun policies should be but disagree on which policies are likely to achieve those objectives? Or do they agree on how policies likely affect outcomes but disagree about the most important goals to pursue via policy?

Our results suggest that the differences in each group's overall opinion of the policies are associated with different beliefs about what the true effects of the policies will be.

Our approach allowed us to compare these alternative explanations. Our results suggest that the differences in each group's overall opinion of the policies are associated with different beliefs about what the true effects of the policies will be, not with differences in which outcomes or objectives the experts care most about. Indeed, both groups overwhelmingly preferred the policies they believed would reduce firearm suicides and homicides. Protecting privacy rights, facilitating participation in hunting and sport shooting, reducing mass shootings, and protecting gun rights appear to be shared secondary priorities.

This finding has important practical implications. It means that scientific evidence about how gun policies affect outcomes may be useful in helping resolve some disagreements among policy experts—and, by extension, among members of the public. That said, we are not suggesting that longstanding and politically contentious disagreements about the true effects of gun policies will be easily overcome when better scientific evidence becomes available. There is compelling evidence that the public and experts may be motivated to discount evidence that disagrees with their own views (or the views of their social groups) if accepting the implications of the new evidence could damage their professional alliances, their status in a group, or their economic well-being (see, for example, a 2016 study by Dan Kahan, a 2017 study by Kahan and colleagues, and a 1993 study by Jonathan Koehler). Indeed, our findings that experts agree on policy objectives but disagree on policy effects could be equally well explained by one or both groups bending their assessments of the likely effects of policies to match their overall opinions of the policies. Nevertheless, given that members of both the permissive and restrictive groups appear to share a set of objectives, and given that there is currently only weak scientific evidence on which to base those judgments, collecting more and stronger evidence about the true effects of policies is, we believe, a necessary and promising step toward building greater consensus around fair and effective gun policies.

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